def add(x, y):
    return x + y


if __name__ == '__main__':
    # case01： 1 + 1 = 2
    print(add(1, 1))
    assert add(1, 1) == 2

    # case02: 1 + 0 = 1
    print(add(1, 0))
    assert add(1, 0) == 1

    # case03: 0 + 0 = 0
    print(add(0, 0))
    assert add(0, 0) == 0
